Campbell CPEC300, Руководство по эксплуатации продукта, Страница: 29 / 175

CPEC300/306/310 Closed-Path Eddy-Covariance Systems
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the sensor head for the CSAT3B sonic anemometer, with the primary
difference being that the CSAT3B can be used as a standalone anemometer
because it includes independent electronics.
The CSAT3A uses three nonorthogonal pairs of transducers to sense the wind
velocity vector. Each pair of transducers transmits and receives ultrasonic
pulses to determine the time of flight, which is directly related to the speed of
sound and the wind speed along the line between the pair of transducers. The
CSAT3A transforms the results into orthogonal wind components u
x
, u
y
, and
u
z
, referenced to the anemometer head.
The CSAT3A also determines the speed of sound for each transducer pair.
These measurements are averaged and converted to sonic virtual temperature
(T
s
) based on the relationship between speed of sound and air temperature. For
more detailed information and specifications, see the CSAT3B manual,
available at www.campbellsci.com .
FIGURE 4-26. CSAT3A sonic anemometer head
4.11.3 Valve Module – CPEC310
The three-valve module, shown in FIGURE 4-14 , is housed in the CPEC310
enclosure and is used to perform manual and automated zero and CO
2
span
checks, and manually and automatically perform a zero and CO
2
span on a
user-defined interval. As described in Section 4.4 , CPEC310
(p. 10)
, H
2
O span
requires a dewpoint generator and cannot be automated.
The CPEC310 zero and CO
2
span inlets are not bypass equipped, meaning that
they flow only when selected. This allows the zero and CO
2
span tanks to be
continuously connected for automatic, unattended operation.